RCA CTC187

[Vince]

Hi!
I'm working on a CTC 187 chassis, without the yoke hooked up, I turn it on
and the 140 volts through the flyback to the horozontal output stays up
witch is normal, then hook up the yoke, and turn it on it drops down to
about 70 volts and very little high voltage,. after a little while the
raster will come on about half the screen and the sound won't come on until
I take the CRT board off the picture tube. The picture tube is good, I
hooked another chassis to it and it worked fine, what other than the
flyback could cause this?
Thank you for any advice you can give me.
Vince

 

[mark]

Vince wrote:

Hi!
I'm working on a CTC 187 chassis, without the yoke hooked up, I turn it on
and the 140 volts through the flyback to the horozontal output stays up
witch is normal, then hook up the yoke, and turn it on it drops down to
about 70 volts and very little high voltage,. after a little while the
raster will come on about half the screen and the sound won't come on until
I take the CRT board off the picture tube. The picture tube is good, I
hooked another chassis to it and it worked fine, what other than the
flyback could cause this?
Thank you for any advice you can give me.
Vince


Either substitute the yoke which you probably don't have another or

how about getting the yoke checked if you have an inductance meter and a
schematic which would tell you the inductances of the horizontal and
vertical windings.

 

[Franc Zabkar]

On Thu, 14 May 2009 19:09:43 -0600, "Vince" <vmschmitt@charter.net>
put finger to keyboard and composed:

I'm working on a CTC 187 chassis, without the yoke hooked up, I turn it on
and the 140 volts through the flyback to the horozontal output stays up
witch is normal, then hook up the yoke, and turn it on it drops down to
about 70 volts and very little high voltage,. after a little while the
raster will come on about half the screen and the sound won't come on until
I take the CRT board off the picture tube. The picture tube is good, I
hooked another chassis to it and it worked fine, what other than the
flyback could cause this?

I don't know about your chassis, but I have seen other sets where an
open B+ capacitor causes the B+ rail to drop under load. You may want
to check what the other secondary rails are doing. An open bulk cap on
the primary side may also produce such a symptom, although in this
case I would think that the secondary rails would also drop in similar
proportion.

- Franc Zabkar
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